For this case we must raise the equation according to the given statement.
Let the variable "x" be the unknown number.
So, three times the number is: 
If to that term is added "6" we have:

The sum of both terms is "12", then:

Thus, the equation is: 
Answer:

Answer:
900m
Step-by-step explanation:
All you have to do is find the difference between the two measurements
500 - (-400)
Then, two negatives create a positive:
500 + 400
= 900
Answer:
180
Step-by-step explanation:
add 1% to 31.50 to get 31.815
then take the total 5276.70 and divide by 31.815
Answer:
3x - (15 x 3) = 90
or
3x - 45 = 90
Explanation:
there are 3 boxes. We don't know how many are in them yet, so we write this as 3x. However, we know that we give away 15 to 3 different teachers. 15 x 3 = 45
Therefore the first part is 3x - 45
We also know that in the end we have 90 left.
So our final equation is:
3x - 45 = 90
Answer: -7.5
Step-by-step explanation:
area = 1/2bh.
area = 1/2(x+6)(5)
area = x/2 + 15
area = x/2 = -15
area = x = -7.5
area = -7.5