Question

what is 7/8a=42? in a equation

Answer 1

7/8a=42
a=42*8/7 (times both sides by 8/7 to cancel the fractions)
a=48

Answer 2

$\dfrac{7}{8}a=42\\ a=42\cdot\dfrac{8}{7}\\ a=6\cdot8\\ a=48$