
3*boys=2*18
3*boys=36
boys=12
12+18=30
total number of students: 30
The formula:
A = bh + L (s1 + s2 + s3)
A: area
b: base
h: height
L: length
s1: side 1 (cross-sectional area)
s2: side 2 (cross-sectional area)
s3: side 3 (cross-sectional area)
Here’s an example (see attached image)
A = (4 x 6) + (12 x [7 + 7 + 4])
A = (24) + (12 x 18)
A = 24 + 216
A = 240cm^2
I hope this helped? Comment if you need more explanation or anything!
The number is -13.
In order to find this, we first need to make each part of the statement into a mathematical statement.
Twice the difference of a number and 2.
2(x - 2)
Three times the sum of the number and 3
3(x + 3)
Now we can set them equal to each other and solve.
2(x - 2) = 3(x + 3) ----> Distribute
2x - 4 = 3x + 9 ------> Subtract 2x from both sides
-4 = x + 9 -----> Subtract 9 from both sides
-13 = x
move the decimal point 2 places to the left
42.6 /
= 0.426
Yes; his answer is correct.
John can do this by multiple ways, but most likely he just remembered this one. Here are some ways.
1. He used his fingers; he put 1 finger, then another finger, and got 2 fingers up. The answer is 2.
2. He remembered it; usually Kindergarteners learn this and this is very easy to remember.
3. He used the things around him; I have 1 crayon then add another, how many do I have? 2.