Δabc is reflected across the x-axis and then translated 4 units up to create δa′b′c′. what are the coordinates of the vertices of δa′b′c′ ?

changing the sign of y coordinates and then adding 4 units to them will give you translated image

Step-by-step explanation:

The translation happens in two phases. First one the reflection across x axis and the second one shifting 4 units upward

let us see them one by one.

1. Reflection along x axis.

When the triangle will be reflected along x axis, it is the y coordinates which are going to be changes

the y coordinates will now be the negative of what they were before reflection .

2. The upward shifting of the reflected image. In this process the x coordinate will again remain the same but we add 4 units to each coordinates of y in all the three vertices