Use a variable or consumption to solve.
Tom bought 5 apples and 4 pears for $3.80. Jerry bought 10 apples & 5 pears. Jerry paid with a $10 bill and got $3.90 back as change. How much is 1 pear?
Let's assume the cost of 1 apple is A.
Therefore, the cost of 1 pear is P.
From the given information, we can form the following equations:
5A + 4P = 3.80 (equation 1) - Tom's purchase equation
10A + 5P = 10 - 3.90 (equation 2) - Jerry's purchase equation
To solve this system of equations, we can use the method of consumption.
We start by multiplying equation 1 by 2 to eliminate the coefficients of A:
10A + 8P = 7.60 (equation 3)
Next, we subtract equation 3 from equation 2 to eliminate the term with A:
(10A + 5P) - (10A + 8P) = (10 - 3.90) - 7.60
-3P = -3.70
Now, we divide both sides of the equation by -3 to solve for P:
P = -3.70 / -3
P = 1.23
Therefore, the cost of 1 pear is $1.23.