Answer:
2.3lego
Explanation:
We can walk through this problem using the cross multiplication method
First 3 1/2 lego is same as 3.5lego
Hence If
Johnny builds 3.5lego in 60min
He can build xlego in 40min
Crosss multiplying we have
Xlego *60= 3.5*40
Xlego= 140/60= 2.3lego