So it is really easy to solve firstly we can see how much does the first 10 boxes make which makes around 55$ obviously. Secondly 45$ for the next 10 boxes.
So for now we can simply calculate that we have spent around 100$ which means 20 boxes. The remaining money left is 77$ so we can buy 77/3.5 = 22 only 22 boxes with that money. Hence a total of 42 boxes.
Answer: x = -2
Steps/work provided down below. Please let me know if you have any further questions! :)
They have 136 cans left.
175+58-97=?
175+58=233
233-97=136