Marco and his dad went strawberry picking. Together they collected strawberries that weighed 36 pounds. On the way back Marco ' dad lost 8 pounds of strawberries. Marco's strawberries now weighed 12 pounds. How much did his dad's strawberries weigh now?
Marco and his dad went strawberry picking. Together they collected strawberries that weighed 36 pounds. On the way back Marco's dad lost 8 pounds of strawberries. Marco's strawberries now weighed 12 pounds. How much did his dad's strawberries weigh now?

Let's denote Marco's strawberries as $x$ and his dad's strawberries as $y$. 

We know that: 
$x + y = 36$
$x = 12$
$y - 8 = 28$

And we need to find: 
$y = ?$

$y = x + y - x = 12 + 28 - 12 = 28$