Question

Two angles $a\text{and}b$ form a linear pair. If $2a-3b={60}^{\circ }$ then $5b=$____ degrees.

• A. ${120}^{\circ }$
• B. ${180}^{\circ }$
• C. ${240}^{\circ }$
• D. ${300}^{\circ }$

Answer 1

The correct option is D ${300}^{\circ }$

Given that,

$2a-3b={60}^{\circ }$

Also if they form a linear pair, then

$2\times ({180}^{\circ }-b)-3b={60}^{\circ }$ $\because (a={180}^{\circ }-b)$

$\Rightarrow {360}^{\circ }-2b-3b={60}^{\circ }$

$\Rightarrow 5b={300}^{\circ }$