Question

The sum of twice a number and 13 is 75

Answer 1

So what they are saying is the sum of 2x +13=75
Therefore we can just solve for 2x, our unknown value.
2x+13=75 now subtract 13 and divide by 2 from both sides of equation to not change the equation
x+13-13=75-13
This leaves us with
x=(75-13)/2=31 therefore x=31 or our unknown value is 31.

I hope this helped. Any questions please just ask. Thank you.