First, put the equation of the line given<span> into slope-intercept form by solving for y. You get y = 2x +</span>5<span>, so the slope is –2. </span>Perpendicular lines<span> have opposite-reciprocal slopes, so the slope of the </span>line<span> we want to find is 1/2. Plugging in the </span>point given<span>into the </span>equation<span> y = 1/2x + b and solving for b, we get b = 6.</span>
4b=a then plus 10 to see if the age holds true to 3b=a in ten years. Then since the question is how old is she today? You must either add 6 to young age (of20) or minus 4 from the older (of 30).
So Betty would be 26 today.