One number is two times another. the sum of the number is 90 what are the two numbers

1st number is x
other number is 2 times = 2x
sum of the numbers is 90: x + 2x = 90

Solve for x
x + 2x = 90
3x = 90
x = 30
First number = 30
second number = 2x = 2 (30) = 60

One number is 2 times another
x=2y

sum is 90
x+y=90

easy
x=2y
sub 2y for x
2y+y=90
3y=90
divide both sides by 3
y=30

sub back
x=2y
x=2(30)
x=60

the numbers are 60 and 30