This is a weird question but I believe sense you did bring the money then you are going to buy lunch.
7/8 × c ⇒ substitute ⇒ turn 8 into a fraction
7 8 56
___ × ___ = _____ = 7
8 1 8
Your answer is 7
CscA = 1/sinA
CosACscA = cosA × 1/sinA = cosA/SinA = cotA
−<span>2.8
</span>Okay so "0.9x-1.3=-3.1" x=-2
<span><span><span>0.9x</span>−1.3</span>=<span>−3.1
</span></span>add 1.3 to both sides
<span><span><span><span>0.9x</span>−1.3</span>+1.3</span>=<span><span>−3.1</span>+1.3
</span></span><span><span>0.9x</span>=<span>−1.8
</span></span>divide both sides by 0.9
<span><span><span>0.9x/</span>0.9</span>=<span><span>−1.8/</span><span>0.9
</span></span></span>x=<span>−2</span>
So if you plug in -2 into "x-0.8" you get −2.8
<span>=<span><span>−2</span>−0.8
</span></span><span>=<span><span>−2-</span><span>0.8
</span></span></span><span>=<span>−2.8
</span></span>Hope this helps.