Question

5 zidari contruiesc in 90 zile o casa. In cate zile vor construi 30 de zidari aceeasi casa?

Answer 1

5z............90zile
30z............x  sunt invers proportionale

x=5*90/30
x=5*3=15 zile

Answer 2

5 ZIDARI...............................90 ZILE

30 ZIDARI.................................X

X=5*90/30

X=15