The HCF is the Highest Common Factor of a number in this case 54. This is the highest number times another number which = 54. The HCF for 54 is 18.
Change the order of integration.
Substitute 
and 
.
<span><span><span>3x</span>+<span>4y</span></span>=8
</span>Add -4y to both sides
<span><span><span><span>3x</span>+<span>4y</span></span>+<span>−<span>4y</span></span></span>=<span>8+<span>−<span>4y</span></span></span></span><span><span>3x</span>=<span><span>−<span>4y</span></span>+8
</span></span>Then you divide both sides by 3
<span><span><span>3x/</span>3</span>=<span><span><span>−<span>4y</span></span>+8/</span>3</span></span><span>x=<span><span><span><span>−4/</span>3</span>y</span>+<span>8/3
</span></span></span>And your answer is ...
<span>x=<span><span><span><span>−4/</span>3</span>y</span>+<span>8/<span>3</span></span></span></span>
I assume you mean the inverse function. To find the inverse function of a given function, start from the expression 
and solve for x:
Multiply both sides by 4:
Divide both sides by 3:
So this is the inverse function.
