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.
