2 Remainder 2 because 14 divided by 6 is 2 remainder 2
So first write out the expression:

take two 10's from the top to cancel with the two 10's on the bottom.
3.9/1.3 is 3.
The answer is 3*10^3
X = low-energy lamp
y = high-energy lamp
1) 4x + 5y
2) 120= 4x + 5y