Let's solve each equation step by step:

1) 16.5 - (t + 3.4) = 4.9

First, we can simplify the left side by distributing the negative sign:

16.5 - t - 3.4 = 4.9

Now, we can combine like terms:

13.1 - t = 4.9

Next, we isolate the variable t by subtracting 13.1 from both sides:

-t = -8.2

Finally, we can solve for t by multiplying both sides by -1:

t = 8.2

2) r + 16.23 - 15.8 = 7.1

First, we can combine like terms on the left side:

r + 0.43 = 7.1

Now, we isolate the variable r by subtracting 0.43 from both sides:

r = 6.67

Therefore, the solutions to the two equations are:

t = 8.2
r = 6.67