Equations, unknown numbers and factors
Answers are for parents and teachers.
1
Write an expression for “7 more than 3 times a number n”, and find its value when n = 2.5.
3 × n + 7. For n = 2.5: 3 × 2.5 + 7 = 7.5 + 7 = 14.5.
2
Solve 2.75 + a = 6.
a = 6 − 2.75 = 3.25.
3
Solve 7 × b = 5.6.
b = 5.6 ÷ 7 = 0.8. Check: 7 × 0.8 = 5.6.
4
A baker puts 12 rolls on each tray and bakes 84 rolls. Write an equation with t for the number of trays and solve it.
12 × t = 84, so t = 84 ÷ 12 = 7 trays.
5
List all the factors of 28 and of 45.
28: 1, 2, 4, 7, 14, 28. 45: 1, 3, 5, 9, 15, 45.