THE BEST ANSWER IS D. TWO GRANDFATHERS AND A GRANDMOTHER CAN NIT A...

31. - PROBLEMS PRACTICE PHẦN 10 PPSX
PROBLEMS PRACTICE PHẦN 10 PPSX
31. The best answer is D. Two grandfathers and a grandmother can nit a sweater in 3 days, therefore they can nit 2 sweaters in 6 days. Because two grandfathers can nit 1 in 6 days then the other sweater is done by the grandmother, she can nit 1 sweater in 6 days.