Please help solve and explain it, thank you.

Question

1. Juan, Steve and Gabriella bought a total of 30 markers at an art store. Juan bought 3 more markers than Steve. Gabriella bought 7 times as many markers as Steve. How many markers did each buy?

2.

Answer 1

j+s+g = 30
j = s+3
g = 7s

s+3 + s + 7s = 30
9s = 27
s = 3

so, j=6 and g=21