Answer:
y = 5
Explanation:
Since the triangle is equilateral then its sides are congruent (equal )
equate the 2 sides with x as a variable and solve for x
7x - 35 = 3x + 5 ( subtract 3x from both sides )
4x - 35 = 5 ( sdd 35 to both sides )
4x = 40 ( divide both sides by 4 )
x = 10
Then the side 3x + 5 has length
3(10) + 5 = 30 + 5 = 35 so
x + 5y = 35 ( since the sides are equal ) , that is
10 + 5y = 35 ( subtract 10 from both sides )
5y = 25 ( divide both sides by 5 )
y = 5