Arithmetic · real student question

Evaluate -2 x (-4) - (-4) + 3 - (-3) x 5 using the order of operations.

Question

Evaluate

2×(4)(4)+3(3)×5-2\times(-4)-(-4)+3-(-3)\times 5

using the order of operations.

Step-by-step solution

  1. Decide the order before computing anything. There are no brackets to evaluate and no exponents, so the order of operations says: all multiplications first, then the additions and subtractions from left to right. The parentheses here only mark negative numbers — they are not grouping operations to be worked out.

  2. Do the two multiplications. A product of two negatives is positive, and a negative times a positive is negative:

    2×(4)=+8,(3)×5=15.-2\times(-4)=+8,\qquad (-3)\times 5=-15.

    Substituting these back, the expression becomes

    8(4)+3(15).8-(-4)+3-(-15).

    Keep the surrounding signs attached when you substitute: the 15-15 replaces (3)×5(-3)\times 5, so the term is (15)-(-15), not 15-15.

  3. Convert every "subtract a negative" into an addition. Subtracting a negative reverses direction twice, so a(b)=a+ba-(-b)=a+b:

    8(4)=8+4,(15)=+15.8-(-4)=8+4,\qquad -(-15)=+15.

    The expression is now free of double signs:

    8+4+3+15.8+4+3+15.

    This is where most errors happen; writing the double-negative conversion as a separate line makes it much harder to lose a sign.

  4. Add left to right. Accumulating one term at a time:

    8+4=12,12+3=15,15+15=30.8+4=12,\qquad 12+3=15,\qquad 15+15=30.

    So the value of the expression is 3030.

  5. Re-check by grouping differently. Addition is associative and commutative, so pairing (8+15)+(4+3)=23+7=30(8+15)+(4+3)=23+7=30 must give the same total — and it does. Because every term ended up positive, the answer had to exceed the largest single term 1515, which is a quick plausibility test.

Answer

3030

Need to solve a different problem like this? Open the solver →