Complementary angles add up to 90 degrees.
So to find A you would need to add A and B together and equal it to 90 (3x+25+5x-7=90)
Combine like terms together (8x+18=90)
Subtract 18 from night sides (8x=72)
Divide by 8 on both sides (x=9)
Then to find A substitute x into its equation (3(9)+25)=(27+25)=52
A=52 I think
So first, we want to substitute in 15 to all the x variables.
So,
3x - 8y = 5
Becomes
3 * 15 - 8y = 5
Or,
45 - 8y = 5
So here, you can subtract 45 from both sides to move all like terms to one side.
-8y = 5 - 45
And then simplify:
-8y = -40
Then divide both sides by -8
y = 5
For this case, what you should see is where the graph cuts the x-axis.
Notice that the graph cuts to the x axis in three different points.
Then the value of x that is in the domain of the function in this case is:
x = 1
For this value of x the function is zero.
Answer:
x = 1
