I need help.

Question

The sum of a number times 6 and 9 is equal to 4.

 

Use the variable y for the unknown number.

Answer 1

The sum of  can be interpreted as a sum in parantheses.

 

So, in your problem The sum of a number times 6 and 9  is  (6y +9)

 

Therefore the problem is (6y+9) = 4

 

6y+9 = 4  subtract 9

 

6y =  -5    divide by 6

 

y = -5/6

 

 

One might ask why did we put paratheses around 6y+9 if we just removed them.

Consider the following similar question

 

 The product of 2 and the sum of a number times 6 and 9 is equal to 4.

 

The paratheses would be very important here because of the product statement

 

2(6y+9) = 4

 

So adding them when not necessary and then just dropping helps you remember to put them any time you see the words SUM OF or DIFFERENCE OF