Answer key · Set C
Two-Step Expressions
12n + 3 Twice n is 2n, and 3 more than that is 2n + 3. Try n = 5: twice 5 is 10, and 3 more is 13.
22(n + 3) The sum n + 3 comes first, so it goes inside the brackets, and then it is doubled.
313 2 × 5 = 10, and 10 + 3 = 13.
418 The brackets first: 4 + 2 = 6. Then 3 × 6 = 18.
53x + 5 Three parts of x is 3x, and then there is one part of 5: 3x + 5.
63x + 1 Try 3x + 1: 3 × 2 + 1 = 7, 3 × 4 + 1 = 13 and 3 × 6 + 1 = 19. The rule x + 5 fits 2 → 7 but not 4 → 13.
716 x is 5, so 3x + 1 is 3 × 5 + 1 = 16.
8False They match only for some numbers. For n = 2, 2n + 3 is 7 but 5n is 10.
91-A, 2-B, 3-D, 4-C Each story tells which operation to use with p.
102l + 6 The distance around is l + 3 + l + 3, which is 2l + 6.
11n + n and 2n n + n is two n's, which is 2n. But n² means n × n, and n + 2 is not 2n.
1231 4b + 7 with b = 6: 4 × 6 = 24, and 24 + 7 = 31.
13Your own words: a grown-up reads it.
Mark each answer, count the right ones and write the score on the sheet.