Twice a number plus twice a second number is 310. The difference between the numbers is 55. Find the two numbers.
+122 Let x be the large number and y the smaller number. we know that 2*x+2*y =310 and that x-y=55 which can also be written as y=x-55
2x+2y=310
Divide by 2
x+y=155
Since y=x-55 we can substitute y for this and get
x+x-55=155
2x=155+55
2x=210
x= 105
y= 105-55 => y=50
Check by 105*2+50*2 => 210+100=310
cheers
