Full Answer.
If the triangle is an equilateral triangle, then all three angles are exactly 60 degrees each. A right-angled triangle has one angle of 90 degrees, which is the right angle, with two more angles that total 90 degrees when added together.
So you have a right angle triangle. You need to use trig for this, as you have two values you can figure out a third.
You know that you have
90 deg. angle
19 deg. angle
Therefor you have 71 deg. angle
sin19 = x/15
15sin19 = x
x = 2.2
Now do Pythagoras c^2-b^2=a^2
a = 14.8
So the sides are 2.2 and 14.8 units long. (If these numbers are wrong tell me and I'll edit answer)
x=ferns ; y=ivy
12x+8y=260
6x+15y=240
x=60 -(15/6)y
12(60+ (15/6)y + 8y = 260
x=60 -(15/6)y
720 - 30y + 8y = 260
x=60- (15/6)y
-30y +8y= 260-720 ==> -22y= -460
x=60 -(15/6)y
y= (-460)/(-22)= 20.9090909091
y=20.90
x=60 -(15/6)×20.90= 7.75
×(ferns)=7.75$
y(ivy)=20.90$
Point six repeatedly so 0.16666666666... so just put a bar over the six
