請用中文解釋怎樣做?

Area of triangle = 1/2 * 底 * 高

因為 BY:YC = 4:3 同埋有相同高度
(altitude = perpendicular from A to BC)
(高 = 由A畫去BC既垂直線) <--中文唔知係咪咁=.=
[因為高度一樣, 面積既比例就係底邊既比例]
所以Area of triangle ABY:Area of triangle ACY = 4:3

Area of triangle ABY = 70 * 4/3 = 40

因為 AX:XB = 3:2 同埋有相同高度
(altitude = perpendicular from Y to AB)
(高 = 由Y畫去AB既垂直線) <--中文唔知係咪咁=.=
[因為高度一樣, 面積既比例就係底邊既比例]
所以Area of triangle AXY:Area of triangle BXY = 3:2

Area of triangle AXY = 40 * 3/5 = 24