Question

Francesca tried to evaluate an expression. Here is her work:
3(5)2–18÷3
=
3(25)–18÷3 Step 1
=
75–18÷3 Step 2
=
57÷3 Step 3
=
19 Step 4
Is Francesca's work correct?

Answer 1

No — Francesca is incorrect.

Errors:
- Step 1: 3(5)2 is 3 × 5 × 2, not 3 × 5^2. So 3(5)2 ≠ 3(25).
- Step 3: In 75 − 18 ÷ 3 the division must be done before subtraction, so 18 ÷ 3 = 6, not doing 75 − 18 first.

Correct evaluation using order of operations (multiply/divide left to right, then add/subtract):
3(5)2 − 18 ÷ 3 = 3×5×2 − 18÷3 = 30 − 6 = 24.