the student has left 75 because if you add 5 and 70 it gives you $75 that's how much the student had left.
Answer: An equations is a number, a variable, or a combination of numbers and variables and operational symbols. An equation is made up of two expressions connected by an equal sign.
Example Expression: 8x+5y-3x-5
Example Equation: 5x-4=x
Hope this helps a little bit:)
The answer is in the attached image