The difference between the heights of two trees is 20 cm. Ten years ago, the taller one was thrice as taller as the shorter one. The present height of the taller tree is  Options:	A) 300cm	B) 15cm	C) 20cm	D) 10cm	E) 40cm
Let their heights of x cm and (x + 20) cm respectively.   Then, (x + 20) - 10 = 3(x - 10)   ⇔ x +10= 3x - 30   ⇔ 2x = 40   ∴ Present height of taller tree = (20 + 10)= 
<gadget id="calculator">(20 + 10)</gadget>
<output>30</output>
30cm.   300cmnswer :30cm
<result>A</result>
The difference between the heights of two trees is 20 cm. Ten years ago, the taller one was thrice as taller as the shorter one. The present height of the taller tree is