Question 384450
let x = the amount (ml) of 45% mixture should be mixed with the 80% solution
then 60-x =  the amount (ml) of 80% mixture should be mixed with the 45% solution
mixing these  two amounts together will give 60 ml of a 60% solution.

,45x+.8(60-x) =.6(60)
.45x +48-.8x =36
.35x = 12x 
x =12/.35 =34.29 ml
60-x =25.71 ml

ans: 34.29 ml of the 45% mixture should be mixed with 25.71 ml of  the 80% mixture to get 60 ml of a 60% solution of hydrochloric acid