first we should find the percentage of the tax for the items Mike bought :
[tex] \frac{42}{100} = \frac{2.94}{x} \\ x = \frac{2.94 \times 100}{42} = \frac{294}{42} = 7 [/tex]
the tax of the items are 7% of the price
so we find this percent for 58
[tex] \frac{58}{100} = \frac{x}{7} \\ x = \frac{7 \times 58}{100} = \frac{406}{100} = 4.06[/tex]
so now you can add the tax to the price:
[tex]58 + 4.06 = 62.06[/tex]
hope you understand it
good luck
