Answer:
x=1
Step-by-step explanation:
(7x-1)+(2x-1)=7
7x+2x-1-1=7
7x+2x=7+1+1
9x=9
9x/9 = 9/9
x=1
The sin A is equal to 12/13 and the tan (A) is equal to 12/5.
<h3>RIGHT TRIANGLE</h3>
A triangle is classified as a right triangle when it presents one of your angles equal to 90º. The greatest side of a right triangle is called hypotenuse. And, the other two sides are called cathetus or legs.
The math tools applied for finding angles or sides in a right triangle are the trigonometric ratios or the Pythagorean Theorem.
The Pythagorean Theorem says:
. And the main trigonometric ratios are:

The question gives cos (A)=5/13. If cos (A) is represented by the quotient between the adjacent leg and the hypotenuse, you have:
adjacent leg=5
hypotenuse=13
Therefore, you can find the opposite leg of A from Pythagorean Theorem, see below.

Thus, the opposite leg is equal to 12. Now, you can find sin (A) since:

Finally, you can find the tan (A) since:

Learn more about trigonometric ratios here:
brainly.com/question/11967894
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slope-point form:
we need the slope (m) and a point.
y-y₀=m(x-x₀)
Given two point A(x₁,y₂) and B(x₂,y₂), the slope of the line is :
m=(y₂-y₁) /(x₂-x₁)
Example 3:
we can take two points:
A(12,2)
B(13,7)
m=(7-2) / (13-12)=5/1=5
therefore:
y-2=5(x-12)
y-2=5x-60
y=5x-60+2
y=5x-58
answer: y=5x-58
Example 4:
we can take two points.
A(0,0)
B(3,1)
m=(1-0)/(3-0)=1/3
Therefore:
y-0=1/3(x-0)
y=x/3
answer: y=x/3
There a 4 quarts in 1 gallon, so he will fill and empty the container 20 times.