The problem states the shirt is 25% OFF the original price not 25% OF it. Therefore after solving how much of it is 25% which in this case is $5, you would have to subtract that 25% from the original price. 25-5=20. The correct answer is $20.
You are trying so solve <span><span>3^x</span>=8</span> and since 8 is not an integral power of x you need a calculator. it is <span><span>ln(8)/</span><span>ln(3)</span></span>
or <span><span><span>log(8)/</span><span>log(3)</span></span></span>
