Question

The sum of three numbers is 90. The third number is 5 less than the first. The second number is 3 times the third. What are the numbers?

Answer 1

let three number as x,y,z
x+y+z=90 —(1)
z=x-5 —(2)
y=3z —(3)

(3) into (1)

x+3z+z=90
x+4z=90
x=90-4z—(4)

(4) into (2)

z=90-4z-5
5z=85
z=17—(5)

(5) into (4)
x=90-4(17)
x=22

(5) into (3)
y=3(17)
y=51