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1. Two books cost 220 Philippine peso and one cost 20 Philippine peso more than the other. Find the cost of each.
x + y = 220, (1)
x - y = 20. (2)
To solve, add equations (1) and (2).
Then, I think, everybody in Philippine knows what to do next.
2. There are 10 coins in a purse consisting of 5 Philippine peso and 1 Philippine peso denominations.
If the total amount of the coins is 26 Philippine peso then how many coins of each kind are there in the purse.
x + y = 10, (1) (there are 10 coins, x of 5-peso and y of 1-peso)
5x + 1y = 26. (2) (the "value" equation)
Distract equation (1) from equation (2).
From this point, complete the assignment yourself. Good luck!