Area of a triangle is <em>l </em>x <em>w </em>(length x width)
That's 4 cm x 12 cm. Now you could go ahead and figure it out from there, but you have to remember it wants the answer in meters. It tells us that for every 4cm, it is 5m. The easiest way to figure this out is to convert to meters before multiplying. Since 4 cm is 5m, the <em>l </em>becomes 5m. 4 goes into 12 three times. So we would do 5 x 3 to get 15m for the new <em>w. </em>Now we can solve for area.
