Question 14c

fig 1 total → 2 + 3 = 5 fig 2 total → 4 + 5 = 9 fig 3 total → 6 + 7 = 13 fig 4 total → 8 + 9 = 17

figure 1 total → 5 figure 2 total → 5 + 4 = 9 figure 3 total → 9 + 4 = 13 figure 4 total → 13 + 4 = 17

adding number → 4 starting number → 5

formula if adding number is the same

figure number → (total number - starting number) ÷ adding number + 1 = (85 - 5) ÷ 4 + 1 = 80 ÷ 4 + 1 = 21