Page 152 - NUMINO Challenge_M2

2 The frog on the right moved 10 cm to the right, and the frog on the left moved

20 cm to the left, and the space between the frogs increased by 30 cm. The
distance between the frogs after they have moved is 80 cm, so the original
distance can be found by +10+20=80 cm.

The original distance is 50 cm.

20 cm 10 cm

Original
distance

Distance after moving=80 cm

Type Study +7-4=15, so +7=19.

In +7=( ), ( )=19, so =12.

12. -7+4=12-7+4=9.

Problem solving

1 Numbers greater than 4 and less than 9 are 5, 6, 7, and 8. When each of 5, 6,

7, and 8 are multiplied by 6, only 7 and 8 will be greater than 40. When 5, 6, 7,
and 8 are multiplied by 4, only 5, 6, and 7 are less than 30.

The number that satisfies all the descriptions is 7.

2 If is the cost of 1 potato, the cost of 3 potatoes is 3^ . Jane went to the

store with 50 cents, bought 3 potatoes, and received 5 cents in changed, so
3^ +5=50 cents. The cost of 3 potatoes is 3^ =45 cents, and one potato is
15 cents.
If Jane bought 2 potatoes, it would be 2^15=30 cents. If the change she
would receive is , then 30+ =50 cents, and =20 cents.

15Answer Key