An isosceles triangle in which the two equal sides, labeled x, are longer than side y.
the isosceles triangle has a perimeter of 7.5 m.

which equation can be used to find the value of x if the shortest side, y, measures 2.1 m?

2 x minus 2.1 equals 7.5
4.2 plus y equals 7.5
y minus 4.2 equals 7.5
2.1 plus 2 x equals 7.5