como despejar 78.4 = 4.9 * t
78.4 = 4.9t
Divide ambos ladosd con 4.9:
78.4 / 4.9 = 4.9t / 4.9
$${\frac{{\mathtt{78.4}}}{{\mathtt{4.9}}}} = {\mathtt{16}}$$
16 = t