Harry used 76 rods to make a total of 15 octagons and pentagons. An octagon is made by 8 rods and a pentagon is made by 5 rods. How many of each type of shapes did he make?
- Number of octagons
- Number of pentagons
(a)
Assuming all are pentagons,
Number of rods needed for the pentagons
= 5 x 15
= 75
Number of extra rods left
= 76 - 75
= 15
Difference in the number of rods between 1 octagon and 1 pentagon
= 8 - 5
= 3
Number of octagons
= 15 ÷ 3
= 5
(b)
Number of pentagons
= 15 - 5
= 10
Answer(s): (a) 3; (b) 10