Final answer:
The error in the work shown is that the student subtracted 30 from 18, instead of adding them together. To find an expression equivalent to 18 + 30, you simply add the two numbers together:
18 + 30 = 48
Step-by-step explanation:
The error in the work shown is in the expression 18 - 30 = 613 - 10. This expression is incorrect both in its form and result. When looking for an expression equivalent to 18 + 30, addition should be used, not subtraction. The correct expression should be 18 + 30 = 48. The factors listed for 18 and 30 are not relevant to the operation of addition.