The answer for that is .. 17?
In terms of pi means to include pi in your answer. In other words, don't use 3.14 or 22/7 for pi.
The answer is A since there are x egg sandwiches that cost $3.10, y beef that cost $3.35 and z cheese sandwiches that cost $2.85, so buying one more of any of those would mean paying that amount a the number of times you buy it. So 2 of x is $3.10 x 2 = $
The error is in the second step they subtracted 3 from both sides but it was a 3x, which you can not do.
Correction.
9x+18+3x=1
12x+18=1
12x=-17
x=-17/12
