Question

one number is five times another.Their sum is 90. what are these two numbers?

Answer 1

Let numbers be x and y,
If number x is five times number y, then x=5y....eq.1
And if x+y =90....eq.2 then we have to solve the system.
X=5y...eq 1
X+y=90...eq.2
X+y =90...eq.2 substitute x from eq. 1
5y+y=90
6y=90
Y=90/6
Y=15.
Now back to eq.1 and find x
X=5y....eq.1
X=5×18
X=75
So the two numbers are 15 and 75