Another problem solving question....
cecil and Rea went to the supermarket. Cecil bought a kilo of chicken that cost P82 cheaper than a kilo of beef. Rea bought 5 kilos of beef and 2 kilos of chicken for P1,803.
a. How much is a kilo of beef?
b. kilo of chicken
c. How much is the cost of all chickens?
thanks again...


Sagot :

We let X be the price of a kilo of beef and Y be the price of a kilo of chicken. We now write: Y = X - 82 and 5X + 2Y = 1803. A.) We now substitute the first equation to the 2nd equation to get X: 5X + 2(X - 82) = 1803 --> 7X - 164 = 1803 --> 7X = 1967 --> X = 281 pesos. B.) Y = 281 - 82 = 199 pesos. C.) The total kilos of chicken bought are 3 kilos, so we have: 3(199 pesos) = 597 pesos.
Let x be the price of a kilo of beef
x-82 the price of a kilo of chicken

If Rea bought 5 kilos of beef then =  5(x)
and 2 kilos of chicken then = 2(x-82)

If it all costs P 1,803:
2(x-82) + 5(x) = 1,803 
2x-164+5x=1,803  Combine similar terms 
7x=1,803+164  Transpose and combine similar terms again
7x/7 = 1,967/7  Divide
x=281

Then a kilo of beef is P281
Then a kilo of chicken is P281-P82 = P199
And 2 kilos of it is P398