Well i think this is it but I am not really sure what your teacher is after 

$$\\2310 - 1293\\
\approx 2000-1000\\
\approx 1000\\\\\\
987-213\\
\aaprox 1000-200\\
\approx 800$$

lbs is pounds

what are you trying to do?

T=t^0-a(z-z^0)

I think I am being asked to make a the subject of the formula.

$$\\T=t^0-a(z-z^0)\\
T=1-a(z-1)\\
T=1-az+a\\
T-1=a-az\\
T-1=a(1-z)\\\\
\dfrac{T-1}{1-z}=a\\\\
a=\dfrac{T-1}{1-z}\\$$

(1/2) (4p+8)-(p+9)

$$\\(1/2) (4p+8)-(p+9)\\
=2p+4-(p+9)\\
=2p+4-p-9\\
=p-5$$

There is no formula

 (1.23)(3.46)/3.96

1.23 x 3.46 / 3.97

$${\frac{{\mathtt{1.23}}{\mathtt{\,\times\,}}{\mathtt{3.46}}}{{\mathtt{3.97}}}} = {\mathtt{1.071\: \!989\: \!924\: \!433\: \!249\: \!4}}$$

I think this is what you are being asked.

$44.64 to $38.08

$${\frac{{\mathtt{4\,464}}}{{\mathtt{3\,808}}}} = {\frac{{\mathtt{279}}}{{\mathtt{238}}}} = {\mathtt{1.172\: \!268\: \!907\: \!563\: \!025\: \!2}}$$

You just want the fraction answer in the middle.

Yes Rosala, I don't understand either!

(-1.42)^(1/7)

This is the web2 calculator ouput

$${\left(-{\mathtt{1.42}}\right)}^{\left({\frac{{\mathtt{1}}}{{\mathtt{7}}}}\right)} = \underset{{\tiny{\text{Error: not real}}}}{{{\left(-{\mathtt{1.42}}\right)}}^{{\mathtt{0.142\: \!857\: \!142\: \!857\: \!142\: \!9}}}}$$

However, this is the answer (approx because it is an irrational number)

$${\mathtt{\,-\,}}\left({\left({\mathtt{1.42}}\right)}^{\left({\frac{{\mathtt{1}}}{{\mathtt{7}}}}\right)}\right) = -{\mathtt{1.051\: \!369\: \!751\: \!024\: \!905\: \!2}}$$

check:

$${\left(-{\mathtt{1.051\: \!369\: \!751\: \!029\: \!052}}\right)}^{{\mathtt{7}}} = {\mathtt{\,-\,}}{\frac{{\mathtt{71}}}{{\mathtt{50}}}} = -{\mathtt{1.420\: \!000\: \!000\: \!039\: \!206\: \!4}}$$

I think that this can only work if the denominator of the power is an odd number.

Most calculators have a real problems with this - sometimes you really do have to use your own brain. 

I invite further comment on this one.   

Dragon stop being so slack and do some thinking for yourself !!!!!  

It is not reliable you do not have enough money!