When simplifying equations I like to use a little strategy called pemdas to remember the order
parenthesis
equation
multiply
divide
add
subtract
(multiply/divide and addition/ subtraction depend on which one's first in the equation though but multiply/ dividing is always before adding/subtracting)
Since parenthesis is first in pemdas you need to do what's in the parenthesis first (2+54x6)
But since theres two problems in the parenthesis you need to figure out what's next in pemdas. There's no equations so it's not that. Therefore, the first thing you need to do is 54x6.
42/3=14 (price of one shirt) 100-20=80 (robert buys 5 shirt each costing 80% of the original price) 14/100x80=11.20 (price of one shirt with a 20% discount) 11.20x5=56 cost of all 5 shirts
