1: Solve for either x or y in one of the equations. So x + y = -1 is y = -x -1
2: substitute the new equation in the opposite equation. So x - (-x - 1) = 7
3: distribute the negative. X + x + 1 = 7
4: combine like terms. 2x + 1 = 7
5: solve for x. Subtract 1 on both sides. 2x = 6
6: divide by 2 to get x by itself. X = 3
7: plug the new value of x into one of the ORIGINAL equations. 3 + y = -1
8: solve for y. Subtract 3 on both sides.
Y = -4
9: the solution is written as (x,y) so the solution would be (3, -4)
#22. We are given that y = 1/4. So, we want to plug this value into the expression 15/y:
15/(1/4)
When you divide by a fraction, you should follow the rule “flip the guy and multiply”. Basically, 15/(1/4) = 15 * 4 = 60.
The answer for #22 is (D).
#23. We can use a proportion:
(The shaded area)/(entire circle area) = (360 - 60)/360
But, we don’t have to find the areas of the region and circle; we can just solve the fraction:
(360 - 60)/360 = 300/360 = 30/36 = 5/6
The answer for #23 is (A).
540 (100 centimeters = 1 meter, so 54 x 100 = 540.)
1. I feel the need to explain things first before I write the numeric value.
Let x be the total number of students in the school. 25% of this value is given to be 35.
(0.25)x = 35
The value of x is 140. 75% of this value is the answer which is equal to 105.
2. Let y be the alternative schools. With this, the number of charter schools is 2x - 6 which is equal to 52
2x - 6 = 52
The value of x is 29. Therefore, there are 29 charter schools.
In this case we are dealing with the pythagorean theorm involving right angled triangles. This theorm states that a^2 + b^2 = c^2 which means the square of the hypotenuse (side c, opposite the right angle) is equal to the square of the remaining two sides.
In this case we will say that a = 3963 miles which is the radius of the earth. c is equal to the radius of the earth plus the additional altitude of the space station which is 250 miles; therefore, c = 4213 miles. We must now solve for the value b which is equal to how far an astronaut can see to the horizon.
(3963)^2 + b^2 = (4213)^2
b^2 = 2,044,000
b = 1430 miles.
The astronaut can see 1430 miles to the horizon.
