What is the sum of two numbers is 45 and theire difference is 5

let the two numbers be x and y

x+y=45(equation 1)

x-y=5(equation 2)

from equation (1) y=45-x(equation 3)

substitute 45-x for y in equation 2

x-(45-x)=5

x-45+x=5

x+x-45=5

2x-45=5

2x=45+5

2x=50

x=50/2

x=25

if x = 1, then the answer is 3.5