Melody

10(a+b) + (a+b) = 143

Rosala, you know that      10x+x=10x+1x=11x       right!

This is because 10 lots of something plus one more lots of that same thing = 11 lots of it

Well in the first line the something is (a+b)

10 lots of (a+b) plus one more lot of (a+b) will equal 11 lots of (a+b)

10(a+b) + (a+b) = 143

10(a+b) + 1(a+b) = 143

(10+1)(a+b) = 143

11(a+b)

Will you be alright now.  I assume that was the main problem.   

line up the decimal points and subtract 

Alan was very complimentary of your mathematics that you presented here.

Good luck on your exam tomorrow.  

Depends which calculator.

For the web2 calc on the home page look here.

nothing interesting

neg *neg = pos

-1/6*-5/1 = +5/6

$$\\(3x+2)^2-(5x-2)(2x+3)\\
=9x^2+12x+4-(10x^2+15x-4x-6)\\
=9x^2+12x+4-(10x^2+11x-6)\\
=9x^2+12x+4-10x^2-11x+6\\
=9x^2-10x^2+12x-11x+4+6\\
=\;-x^2+x+10\\$$

This is just the simple interest formula

I=Prt

Try this

$$20 + (8 \div 2)^2 - 7 \times 5 = 1$$