The point (21,32) is on line with slope 1.5 what is the equation of the line ?

We can use the equation y=mx+b to insert the numbers and find the equation. we already know that m, the slope, is 1.5, so we just need to find b.
32=1.5(21)+b
32=31.5+b
Subtract 31.5 from each side: 32-31.5=31.5-31.5+b
0.5=b
Now we have both m and b, so the equation is y=1.5x+0.5.