20 points for whoever can solve this!

christopher has $15 in his savings account. he wants to buy a guitar. he plans to save $10 a week. prices for guitars at the music shoppe start at $130.
which number line shows how long christopher will have to save to buy a guitar from the music shoppe?

10x + 15 > = 130
10x > = 130 - 15
10x > = 115
x > = 115/10
x > = 11.5... rounds to 12... the first answer choice 

1. isolate the variable, in this case, d. subtract 35.5 on both sides of the equation.2. 52 subtracted by 35.5 is 16.53. therefore your answer would be d= 16.5this is the basics of pre algebra, isolating variable through adding, subtracting, multiplying, and dividing, if you have any other questions to ask just comment!