Question

Elevii clasei a IV-a se informeaza despre preturile unor obiecte:3 aparate foto de acelasi fel si un laptop costa 2700lei,iar 5 aparate foto si 2 laptopuri,de acelasi fel ca primele costa,4900lei.Cat costa un aparat foto?Dar un laptop?Prin metoda compaatiei va rog !!!!!!! URGENT !!!!!!

Answer 1

Laptops are 1200 each and cameras are 500 each.

Using elimination:
3c+l=2700
5c+2l=4900

We will make the coefficients of l the same by multiplying the top equation by 2:
2(3c+l=2700)
6c+2l=5400

Our system is now
6c+2l=5400
5c+2l=4900

Subtract the bottom equation:
6c+2l=5400
-(5c+2l=4900)

We have
1c=500
So each camera is 500.

Substitute that in our original first equation:
3(500)+l=2700
1500+l=2700
1500+l-1500=2700-1500
l=1200