Timothy A.
1/29/02
Per. 6
Computer Problem #1
Problem: David has 4 boxes of apples. Each box has the same number of apples. After David eats 3 apples, there are 109 apples left in the boxes. How many apples were in each box?
4a-3 =109
+3
= +3
4
4
a= 28
ck. 4a - 3 = 109
4(28) - 3 = 109
112 - 3 = 109
109 = 109
1. First, I make the variable “a” as the number of apples in one original box.
2. Since there are 4 boxes, I multiply “a” by four, which is written, “4a”, this is the original total number of apples.
3. David eats 3 apples, so I subtract 3, which is written, “-3”.
4. Finally, I have the equation, “4a-3=109”. “109” is the number of apples after 3 are eaten.
5. I need to get “a” alone, so I first cancel “-3” by adding 3, which is written by “+3”. Since there is an equal sign, I add 3 on both sides.
6. Next, I need to cancel the “4”, to get “a” alone.”4a” is the same as “4 times a”, so I divide by 4. I divide 4 on both sides because there is an equal sign.
7. Now, I get “a=28”.
8. The checking process is easy. I write out the original problem and fill in “a” with the answer, “28”.
9. I do the math and if I get “109” on both sides of the equal sign, I am right.