Help me with both please

If the measure of xyz is 81 what is the measure of yz

Lance lived in portugal and brazil for a total of 14 months to learn portuguese. he learned an average of 130 new words per month when he lived in portugal, and an average of 150 new words per month when he lived in brazil. in total he learned 1920 new words. write a system of equations to represent the situation. use x to represent portugal, and y to represent brazil

You paid 28.00 for 8 gallons of gasoline. how much would you pay for 15 gallons of gasoline?