Question 1010739
This is really the same as: You have 5 oranges and 4 apples
that cost $4 etc. They are just using plumbers and helpers
Let {{{ x }}} = daily pay for a plumber
Let {{{ y }}} = daily pay for plumber's helper
------------------------------------
(1) {{{ 4x + 5y = 350 }}}
(2) {{{ 5x + 6y = 430 }}}
---------------------
Multiply both sides of (1) by {{{ 5 }}}
Multiply both sides of (2) by {{{ 4 }}}
Subtract (2) from (1)
(1) {{{ 20x + 25y = 1750 }}}
(2) {{{ -20x - 24y = -1720 }}}
-------------------------
{{{ y = 30 }}}
and
(1) {{{ 4x + 5*30 = 350 }}}
(1) {{{ 4x + 150 = 350 }}}
(1) {{{ 4x = 200 }}}
(1) {{{ x = 50 }}}
The daily pay for a plumber is $50
The daily pay for plumber's helper is $30
----------------
check:
(2) {{{ 5x + 6y = 430 }}}
(2) {{{ 5*50 + 6*30 = 430 }}}
(2) {{{ 250 + 180 = 430 }}}
(2) {{{ 430 = 430 }}}
OK
You can check equation (1)