Answer:
Ben needs to mutiply 2 times 4 pennies to get 8 pennies
Step-by-step explanation:
To found 2 times as many pennies as Ben means that his sister found 2 times 4 pennies or:
2 x 4 = 8 pennies
Ben figure out that wrong because he add 2 + 4 = 6 pennies intead of multiply.