The sum of two numbers is 60. One number is 9 times as big as the other. What is the bigger number?
a = smaller number
b = bigger number
One number is 9 times as big as the other means:
b = 9 a
The sum of two numbers is 60 means:
a + b = 60
a + 9 a = 60
10 a = 60
a = 60 / 10
a = 6
b = 9 a
b = 9 ∙ 6 = 54