Question

the sum of two numbers is 105 and their difference is 45 find the number

Answer 1

let x>y
x+y=105 ——(1)
x-y=45
x=45+y——(2)
Sub (2) into (1)
45+y+y=105
2y=60
y=30
x=45+30 
x=75

Answer 2

x+y = 105
x = 105-y
btp
x-y = 45
105-y-y =45
105- 2y =45
-2y = 45-105
-2y =-60( the negative signs get cancelled)
2y=60
y = 60/2
y = 30
sum is 105
therefore the other no. is 105- 30=75
75 and 30 are the 2 no.s
Hope it helps u