Twice a number plus another number is 310. the difference between the two numbers is 55. what are the two numbers

Lets say the first number is x and the second y

twice the first number is 2x plus another number (y) =310
the difference of the numbers (x-y) = 55
we have simultaneous equations here:
2x+y=310
x-y=55

to cancel the y's the signs are different so you add the equations to give
3x=365
divide it by 3 to get:
x=121 and 2/3

using the easier equation x-y=55 we know x=121 2/3
now we substitute to get 121 2/3 -y=55
take 121 2/3 from both sides to get:
-y= -66 2/3
therefore y= 66 2/3

that means x=121.6(recurring) and y= 66.6(recurring)