For every $$7$$ soccer balls Elena bought for the gym, she bought $$4$$ basketballs. If she bought $$35$$ soccer balls, she bought a total ofballs. 
Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Finding the Total Value using Unitary Method
$$7$$ out of $$11$$ balls that Elena bought are soccer balls. If there are $$7\times5 =35$$ soccer balls, then there is a total of $$11\times5=55$$ balls. 