Step-by-step explanation:
look at the picture shown
Answer : x = 20
Explanation :
3x + 2x +20 + 4x - 20 = 180
(3+2+4=9)
9x + 20 - 20
The 20s cancel each other out because one is positive and the other is negative
9x = 180
9x/9 = 180/9
X = 180 divided by 9
X = 20
Answer: 
Step-by-step explanation:
Let be "x" the time in minutes a 150-pound person must walk at 4 mph to use at least 190 calories.
The amount of calories that a 150-pound person uses in 1 minute when walking at a speed of 4 mph is:

Therefore, knowing this, we can write the following proportion:

Finally, we must solve for "x" in order to find its value.
Multiplying both sides of the equation by 190, we get this result:

You can use the identity
cos(x)² +sin(x)² = 1
to find sin(x) from cos(x) or vice versa.
(1/4)² +sin(x)² = 1
sin(x)² = 1 - 1/16
sin(x) = ±(√15)/4
Then the tangent can be computed as the ratio of sine to cosine.
tan(x) = sin(x)/cos(x) = (±(√15)/4)/(1/4)
tan(x) = ±√15
There are two possible answers.
In the first quadrant:
sin(x) = (√15)/4
tan(x) = √15
In the fourth quadrant:
sin(x) = -(√15)/4
tan(x) = -√15