Question

the diagram shows a triangle.
what is the value of y?
y = \square^\circ

Explanation:

Step1: Sum angles to 180°

$(3y-15) + (2y-9) + (2y+43) = 180$

Step2: Combine like terms

$7y + 19 = 180$

Step3: Isolate term with y

$7y = 180 - 19$
$7y = 161$

Step4: Solve for y

$y = \frac{161}{7}$

Answer:

$y = 23$