Here, I'll do the first one for you.
When they are talking about a number, use "x".
Since it says twice a number, you say 2x. Or 3x for three times the number
2x+12=3x-31
Then use algebra to find x. Get the numbers on one side and all the x's on the other.
2x+12+31=3x-31+31
2x+43-2x=3x-2x
x=43
Now do the rest on your own!
Answer:
The diameter will be given by 50 cm ÷ 3.142 = 15.9134 cm
The radius will be 15.9134 ÷2 = 7.9567 cm or about 7.96 cm
The area of a circle is given by \pi × square of radius
Area = 3.142 × 7.96×7.96 = 199.0821 square cm
Answer:
83.5
Step-by-step explanation:

Answer:
The formula for area is length times width.
it's 8m long, and 6m wide. When we multiply it, we get 48m that is for one side of the cube, so we count how many sides there is. There's 6, so we multiply 6 times 48 and the complete surface area for the whole cube is 288m
Answer:

33 gallons of water to begin with.
Step-by-step explanation:
So we essentially are given two coordinates: (6,87) and (21,222). To find an equation, we simply need to find the slope and y-intercept. We know it's a linear equation because it's a steady stream, meaning a constant slope.
The slope is:

So, the rate at which the stream flows is 9 gallons per minute.
Now, let's find the initial amount of water. To do this, we can use point-slope form. Pick either of the two points. I'm going to use (6,87).

So, there were 33 gallons of water in the tank to begin with.