Question

Help please! And thank u

Answer 1

A/7 + a/3 = 10
a = 21

Answer 2

Answer:

$\frac{a}{7} + \frac{a}{3} = 10 \\ \frac{(3a + 7a)}{21} = 10 \\ \frac{10a}{21} = 10 \\ a = \frac{(10 \times 21)}{10} \\ \boxed{a = 21}$

a=21 is the right answer.