Final answer:
To evaluate the expression for x = 12, substitute the value of x and perform the operations in the correct order, following the rules of arithmetic. The value of the expression is -50.
Step-by-step explanation:
To evaluate the expression for x = 12, we substitute the value of x into the expression and perform the operations in the correct order, following the rules of arithmetic. The expression is: x+7-15-3×18. So, substituting x = 12, we have: 12+7-15-3×18. To evaluate this expression, we first perform the multiplication: 3×18 = 54. Then, we perform the addition and subtraction from left to right: 12 + 7 = 19, 19 - 15 = 4, and finally, 4 - 54 = -50. Therefore, the value of the expression for x = 12 is -50.