Hitomi has a total of 30 red and blue bowling balls at her bowling alley. Each red ball weighs 8 lb. each blue ball weighs 9 lb. If the total mass of the blue balls is 49 lb. heavier than the total mass of the red balls, how many red balls does she have???

Let x = # red balls, and 30 - x = # blue balls.

9(30-x) - 8x = 49

Solve for x.

To solve this problem, we need to set up a system of equations based on the given information.

Let's say the number of red balls is "r" and the number of blue balls is "b".

From the information given, we know that:

1. The total number of balls is 30, so we can write the equation:
r + b = 30

2. The total mass of the blue balls is 49 lb. heavier than the total mass of the red balls, so we can write the equation:
9b = 8r + 49

Now we have a system of equations to solve simultaneously.

We can rearrange the first equation to express "r" in terms of "b":
r = 30 - b

Substituting this expression for "r" into the second equation, we get:
9b = 8(30 - b) + 49

Now, let's solve this equation to find the value of "b" and then we can substitute it back to find the value of "r".

Expanding the equation and simplifying, we get:
9b = 240 - 8b + 49

Combining like terms, we have:
17b = 289

Finally, dividing both sides by 17, we get:
b = 17

Now that we have the value of "b", we can substitute it back into the first equation to find the value of "r":
r + 17 = 30
r = 30 - 17
r = 13

Therefore, Hitomi has 13 red balls.

i can't solve for X , it's confusing...