Because 4.7 is the "abbreviation" for 4.70 also 4.7 is the simplified version of 4.70 kind of like a fraction you 4 70/100 simplified is 4 7/10 or 4.7.
I think it is possibly point b
<span><span><span><span><span><span><span><span><span><span><span><span>(</span></span><span><span><span><span><span><span>1</span></span><span><span>⋅</span></span><span><span>3</span></span></span><span><span>+</span></span><span><span><span>1</span></span><span><span><span>(</span></span><span><span><span><span>5</span></span><span><span>i</span></span></span></span><span><span>)</span></span></span></span></span><span><span><span><span><span>−</span></span><span><span>2</span></span></span><span><span>i</span></span></span><span><span><span>(</span></span><span><span><span><span>3</span></span><span><span>+</span></span><span><span><span>5</span></span><span><span>i</span></span></span></span></span><span><span>)</span></span></span></span></span></span><span><span>)</span></span></span><span><span><span>(</span></span><span><span><span><span>3</span></span><span><span><span>−</span></span><span><span>i</span></span></span></span></span><span><span>)</span></span></span></span></span></span><span><span><span><span>5</span></span></span></span><span /></span><span /></span></span></span></span></span><span>1⋅3+15i-2i3+5i3-i5</span>
Slope is -1/2
You can get that by isolating the x by moving it to the other side then divide the y value by the other side.