Helga's summer job put her in charge of the local soccer and basketball programs. To prepare, she ordered 50 balls, making sure there were 10 more soccer balls than basketballs.
s = soccer balls
b = basketball balls
She ordered 50 balls means:
s + b = 50
10 more soccer balls than basketballs means:
s = b + 10
Put this value in first equation.
s + b = 50
b + 10 + b = 50
2 b + 10 = 50
Subtract 10 to both sides.
2 b = 40
b = 40 / 2
b = 20
s + b = 50
s + 20 = 50
Subtract 20 to both sides.
s = 30
30 soccer balls
20 basketball balls